1. Field of the Invention
The present invention relates to a heat dissipation assembly, and more particularly to a heat dissipation assembly consisting of two parts having different heat conductive characteristics.
2. Related Art
Many computer electronic devices such as central processing units (CPUs) generate large amounts of heat. Excessive heat can adversely affect the stability and operation of a computer. Heat generated by a CPU must be dissipated quickly, to maintain normal operation of the computer. Generally, a heat dissipating assembly incorporating a heat sink is mounted on an upper surface of the CPU.
Conventionally, a heat sink has a plurality of fins for enhancing heat convection. The heat sink is manufactured as a single unit, by extrusion. Limitations inherent in the extrusion process restrict the height of the fins which can be formed. Thus the surface area of the fins is limited, and is frequently insufficient for dissipating large amounts of heat.
To overcome the above problem, other conventional devices have been developed. For instance, a copper plate is attached to a bottom surface of the heat sink using thermal tape. A bottom surface of the copper plate is then attached to an upper surface of the CPU. The copper plate has better heat transfer characteristics than the heat sink. However, the heat conductivity of the thermal tape is usually lower than that of the heat sink, and much lower than that of the copper plate. Thus the assembly does not effectively dissipate large amounts of heat generated by the CPU. An example of such heat dissipation assembly is disclosed in U.S. Pat. No. 5,653,280.
Additionally, thermal grease has been used in place of thermal tape, because it has better heat conduction characteristics. However, thermal grease is not adhesive enough to firmly secure the copper plate to the heat sink.
Thus an improved heat dissipation assembly which overcomes the problems of the prior art is desired.
Accordingly, an object of the present invention is to provide a heat dissipation assembly which includes a heat sink and a metal plate attached to a bottom surface of the heat sink, for attaining improved heat conduction.
A further object of the present invention is to provide a heat dissipation assembly which reliably attaches the heat sink to the metal plate.
To achieve the above objects, a heat dissipation assembly includes a heat sink and a metal plate. The heat sink includes a chassis and a plurality of fins. A pair of tabs depends from each of two opposite sides of a bottom surface of the chassis. First and second flanges respectively depend from the opposite sides of the bottom surface, between the tabs. A material with low thermal resistance is arranged between the metal plate and the chassis. The metal plate is attached to the bottom surface of the chassis. The flanges are bent inwardly to fasten the metal plate to the chassis.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed embodiments of the present invention with attached drawings, in which: